We do a fundamentals/fish camp the first week after school is out. Kids are here in the mornings, after lunch we do whatever we can to prep for the fall. After that week, we all go home.
My HD is usually back in the office as soon as administrators report back after the 4th. It's not in his contract, but he still comes in to handle administrative stuff and make sure admin sees him around.
We might have a few informal "meetings" with beverages for show planning during this time, but nothing official. The other AD and I usually come in a few days before student leadership reports for final prep.
Outside of actual band camp days with kids, it's all very loose and built around our schedule. The other AD teaches DCI over the summer. My wife and I usually travel (yay no kids!).
We spend so much time with the band "in-season," it's important to have an off-season.